The emergence of chemically strengthen glass, especially glass that can be manufactured in large thin sheet sizes by fusion forming, has opened up market segments in a variety of consumer areas. These new markets include the use of thin sheet glass in electronic devices for displays, appliances, and automotive components. Examples of potential applications include liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), and the like. In particular, the expanding use of ion exchangeable thin sheet glass in these markets has prompted the desire for shaped three-dimensional glass sheets, with an emphasis on combinations of flat portions with highly curved, localized shapes.
Currently, glass sheets are commonly fabricated by a flowing molten glass to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming process techniques, for example, slot draw, float, down-draw, fusion down-draw, or up-draw. The glass ribbon may then be subsequently divided to provide sheet glass suitable for further processing into a desired application. Subsequent fabrication techniques that allow for modification of the shape of the glass sheet are desirable to extend the number of applications wherein flat glass could be used. A good example is the case of automotive windshields, where current designs are far from simple flat shapes.
However, there are significant challenges to modifying the shape of thin flat glass sheets. For display applications, optical clarity of the glass sheet is extremely important and maintaining the “pristine” nature of the fusion formed surface is critical. Standard molding techniques used for bending and reshaping sheet glass tend to imprint any irregularities the mold tooling may have onto the glass surface, therefore a shaping technique which limits the amount of contact the tooling has with the display area of the glass is preferred. Additionally, the demand for tighter controlled deformations (e.g., bends) and thinner glass sheets, typically 1 mm thickness or less, means that the traditional processes for bending glass sheets are not suitable as they are unable to cleanly create the necessary structures.
Thus, there is a need for processes which allow: retention of a high level of flatness in the desired areas, usually the largest area of the finished product; retention of the pristine aspect of the glass sheet; desired amount of deformation in the areas of interest; and a high level of dimensional control. Embodiments address these needs by allowing for bending and shaping sheet glass using targeted heating optionally with clamping and/or mechanical means to avoid unwanted distortions in the glass sheet while avoiding or minimizing contact with the glass. Such processes can be suitable for reforming glass sheets in a wide range of applications incorporating glass sheets such as appliances (e.g. display applications), automotive, portable electronic devices, or other devices incorporating a reformed glass sheet.